基于3种干旱指标的天水地区干旱演变特征分析

利用1971—2011年天水地区河谷、渭北、关山区3个代表点的气象站资料,以湿润度指数(Mi)、标准化降水指数(SPI)、降水距平百分率(Pa)3种干旱监测指标及等级划分为基础,对天水各气候区的春、夏、秋3个主要作物生长时段干旱气候演变特征进行分析。结果表明,天水春季(3—5月)出现干旱灾害的气候风险最大,各气候区10年中有6~8年出现干旱,中旱以上干旱河谷区10年中有4~5年、渭北区有5~6年、关山区有2~4年出现;夏季(6—8月)干旱风险次之,各气候区10年中有6~7年出现干旱,中旱以上干旱河谷区10年中有2~4年、渭北区有2~3年、关山区有2~4年出现;秋季(9—10月)各等级干旱气候风险出现均较小。各季干旱风险主要出现在20世纪90年代初以后。

Analysis on Characteristics of Drought Evolution in Tianshui Area Based on Three Drought Indexes

Using the meteorological data of three representative points in the Hegu zone,Weiber zone and Guanshan zone of Tianshui area from 1971 to 2011,and based on the three indexes of moisture index (Mi),standardized precipitation index(SPI) and percentage of precipitation anomaly(Pa),the characteristics of drought climate evolution during the growth period of spring,summer and autumn of the three main crops in Tianshui climate zone were analyzed.The result showed that in spring (from March to May) got the biggest probability to have the drought,every climatic zone got 6-8 years had drought in 10 years,drought up to intermediate in Hegu zone got 4-5 years in 10 years,in Weibei zone got5-6 years in 10 years,Guanshan zone got 2-4 years in 10 years.The drought in summer (from June to August) was nest to the spring,every climatic zone got 6-7 years had drought in 10 years,drought up to intermediate in Hegu zone got 2-4 years in 10 years,in Weibei zone got 2-3 years in 10 years,Guanshan zone got 2-4 years in 10 years.In autumn (from September to October) got the less probability to have the drought.The drought risk mainly appeared in after the early 1990s.